KR102455218B1 - Promotes Plastic Adhesion for 2K Polyurethane Adhesives - Google Patents

Abstract

The present invention comprises a resin component (a) and a curing agent component (b) and comprises N-ethyl-2-pyrrolidone and/or methyl-5-(dimethylamino)-2-methyl-5-oxopentano as adhesion promoters. It relates to a polyurethane adhesive composition further comprising an ate. Furthermore, the present invention relates not only to methods of using such polyurethane adhesive compositions, but also to methyl-5-(dimethylamino)- as adhesion promoter for adhesive compositions, preferably for polyurethane-based adhesive compositions, in particular for two-component polyurethane adhesive compositions. 2-methyl-5-oxopentanoate and/or N-ethyl-2-pyrrolidone.

Description

Promotes Plastic Adhesion for 2K Polyurethane Adhesives

The present invention comprises a resin component (a) and a curing agent component (b) and comprises N-ethyl-2-pyrrolidone and/or methyl-5-(dimethylamino)-2-methyl-5-oxopentano as adhesion promoters. It relates to a two-component (2K) polyurethane adhesive composition further comprising an 8. Furthermore, the present invention relates not only to methods of using such polyurethane adhesive compositions, but also to methyl-5-(dimethylamino)- as adhesion promoter for adhesive compositions, preferably for polyurethane-based adhesive compositions, in particular for two-component polyurethane adhesive compositions. 2-methyl-5-oxopentanoate and/or N-ethyl-2-pyrrolidone.

In order to ensure sufficient adhesion of the adhesive to the substrate surface to which the adhesive is applied, an adhesion promoter is usually an additive component included in the adhesive formulation itself or in the form of a primer composition for treating the respective surface prior to application of the adhesive. is used in the form of For example, abietic acid and rosin esters are disclosed as useful tackifiers in polyurethane pressure sensitive adhesive compositions. Esters of rosin, such as pentaerythritol methyl ester, propyl ester, ethylene glycol and glycerol ester, as well as esters of hydroabiethyl alcohol such as its useful as tackifiers for achieving improved adhesive properties of polyurethane pressure-sensitive tapes Benzoic acid and phthalic acid esters are also known in the art.

It is an object of the present invention to provide an alternative adhesion promoter, which results in an adhesive formulation with good adhesion properties to various surfaces.

In this regard, surprisingly, by the inventors of the present invention, the present invention containing N-ethyl-2-pyrrolidone and/or methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate It has been found that the polyurethane adhesive composition exhibits excellent adhesion of the composition to various surfaces to which it is applied, for example to plastic surfaces, in particular to surfaces of polyvinylchloride substrates. Moreover, the results obtained with respect to tensile shear strength are comparable to those obtained for compositions containing commonly used adhesion promoters.

Accordingly, in a first aspect, the present invention comprises a resin component (a) and a curing agent component (b) and as adhesion promoters N-ethyl-2-pyrrolidone and/or methyl-5-(dimethylamino)-2- to a two-component polyurethane adhesive composition further comprising methyl-5-oxopentanoate.

In another aspect, the present invention also relates to methyl-5-(dimethylamino)-2-methyl-5-oxo as adhesion promoter for adhesive compositions, preferably for polyurethane-based adhesive compositions, in particular for two-component polyurethane adhesive compositions. to the use of pentanoate and/or N-ethyl-2-pyrrolidone.

Further preferred embodiments of the invention are set forth in the claims.

In this specification, the terms “a” and “at least one” are synonymous with the term “one or more” and may be used interchangeably.

As used herein, “one or more” refers to at least one and includes 1, 2, 3, 4, 5, 6, 7, 8, 9 or more of the mentioned species. Similarly, “at least one” means one or more, ie, 1, 2, 3, 4, 5, 6, 7, 8, 9 or more. “At least one,” as used herein in reference to any component, refers to a number of chemically different molecules, ie, different types of the mentioned species, but not the total number of molecules. For example, "at least one polyol" means that at least one type of molecule belonging to the definition for a polyol is used and there may also be two or more different molecular types belonging to this definition, but only one molecule of said polyol This does not mean that it exists.

When reference is made herein to the molecular weight of a polymer or a component thereof, such reference refers to the number average molecular weight M _n , unless expressly stated otherwise. The number average molecular weight M _n can be calculated on the basis of end group analysis (OH number according to DIN 53240) or can be determined by gel permeation chromatography according to DIN 55672-1:2007-08 using THF as eluent . Unless otherwise stated, all given molecular weights are determined by end group analysis. The weight average molecular weight M _w can be determined by GPC as described for M _n .

All percentages given herein with respect to compositions or combinations relate to percentages by weight relative to the total weight of each composition or combination, unless expressly stated otherwise.

In the context of the present invention, the term “NCO-reactive” refers to a chemical group capable of reacting with an NCO group. These include in particular groups comprising acidic H-atoms, such as hydroxyl, primary or secondary amino, mercapto or carboxyl groups.

In the present invention, the molar ratio of the sum of the isocyanate (NCO) groups of the polyisocyanate to the hydroxyl (OH) groups of the polyol is also referred to as NCO:OH, unless explicitly stated otherwise.

The polyurethane adhesive composition according to the present invention is a two-component adhesive composition and comprises components (a) and (b), wherein component (a) is a resin component and component (b) is a curing agent component.

In certain embodiments, resin component (a) comprises at least one NCO-reactive prepolymer and curing agent component (b) comprises at least one polyisocyanate. However, in certain other embodiments, resin component (a) comprises at least one NCO-terminated prepolymer and curing agent component (b) comprises at least one polyol. In such embodiments where an NCO-terminated prepolymer is used, the curing agent may include other compounds comprising at least two NCO-reactive groups instead of or in addition to the at least one polyol.

In isolated form, both components (a) and (b) are storage-stable.

For each component, additional additives may be incorporated, provided that they do not react with the reactive groups of other compounds during storage to ensure the stability of the formulation.

In a preferred embodiment according to the invention, the resin component (a) comprises at least one NCO-reactive prepolymer. In a particularly preferred embodiment, the NCO-reactive prepolymer is a hydroxyl-terminated prepolymer. In an even more preferred embodiment, the NCO-reactive prepolymer is a hydroxyl-terminated polyurethane prepolymer.

Suitable hydroxyl-terminated polyurethane prepolymers can be prepared by reacting at least one polyol with at least one polyisocyanate, wherein the at least one polyol is used in a molar excess relative to the sum of the hydroxyl groups to the isocyanate groups. In an alternative embodiment where NCO-terminated prepolymers are used, such prepolymers can be prepared by using at least one polyisocyanate in a molar excess relative to the sum of the isocyanate groups to the sum of the hydroxyl groups of the at least one polyol. . In the following, useful polyols and polyisocyanates are disclosed centered on the first embodiment disclosed above, namely a hydroxyl-terminated prepolymer and a polyisocyanate curing agent, although the same compounds may be used in embodiments in which an NCO-terminated prepolymer is used. to understand that there is

The at least one polyol used in the preparation of the hydroxyl-terminated polyurethane prepolymer can be prepared from a wide variety of commercially available products, such as polyetherpolyols, polyesterpolyols, oleochemical polyols, aliphatic, cycloaliphatic or aromatic. polyols, OH-group containing polymeric or oligomeric compounds such as polycarbonates, polybutadiene, polyacrylates or mixtures thereof.

One group of suitable polyols are polyester polyols which can be prepared by condensation of di- or tricarboxylic acids with an excess of di- or trifunctional alcohols. The carboxylic acid may be an aliphatic, cycloaliphatic, aromatic or heterocyclic carboxylic acid or mixtures thereof. Examples of suitable acids include aliphatic acids such as adipic acid, sebacic acid, glutaric acid, azelaic acid, suberic acid, undecanedioic acid, dodecanedioic acid, 3,3-dimethylglutaric acid, hexahydrophthalic acid; aromatic acids such as phthalic acid, terephthalic acid, isophthalic acid; unsaturated acids such as maleic acid, fumaric acid, dimer fatty acids; tricarboxylic acids such as citric acid and trimellitic acid. Examples of suitable di- or trifunctional alcohols are low molecular weight alcohols such as ethylene glycol, diethylene glycol, neopentyl glycol, hexanediol, butanediol, propylene glycol, glycerol or trimethylol propane, dipropylene glycol, 1,4-butanediol , 1,6-hexanediol, 1,8-octanediol, 1,10-dicanediol, 1,12-dodecanediol, 1,4-hydroxymethyl cyclohexane, 2-methyl propane-1,3-diol , butane-1,2,4-triol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol and polybutylene glycol as well as glycerol, trimethylolpropane, or the above including, but not limited to, mixtures of those

Another group of suitable polyester polyols is based on ε-caprolactone, also called polycaprolactone, or a hydroxycarboxylic acid, for example ω-hydroxycaproic acid. Such polyols contain at least two OH groups, preferably terminal OH groups.

Another group of polyester polyols useful in the present invention are the so-called oleochemical polyols. Such polyester polyols may be prepared by, for example, complete ring opening of an epoxidized triglyceride of a fatty mixture comprising at least a partially olefinically unsaturated fatty acid and one or more alcohols having 1 to 12 alcohols followed by partial transesterification of the triglyceride derivative. by providing an alkyl ester polyol having 1 to 12 C atoms in the alkyl radical. Another group of such preferably suitable polyols based on natural products are the dimer diols as well as castor oil and its derivatives.

Another group of polyols are polyacetals. Polyacetals are understood to be compounds obtainable by reacting glycols, for example diethylene glycol or hexanediol or mixtures thereof, with formaldehyde. Polyacetals suitable for the purposes of the present invention can also be obtained by polymerizing cyclic acetals.

Another group of polyols are polycarbonates. Polycarbonates can be prepared by, for example, diols such as propylene glycol, butane-1,4-diol or hexane-1,6-diol, diethylene glycol, triethylene glycol or tetraethylene glycol or mixtures of two or more thereof. It can be obtained by reaction with a diaryl carbonate, for example diphenyl carbonate or phosgene.

Another suitable polyol component is a polyether polyol which is the reaction product of a low molecular weight polyhydric alcohol with an alkylene oxide. The alkylene oxide preferably contains 2 to 4 carbon atoms. Suitable reaction products of this type are, for example, ethylene glycol, propylene glycol, isomeric butane diol, hexane diol or 4,4'-dihydroxydiphenyl propane with ethylene oxide, propylene oxide or butylene oxide or a reaction product of a mixture of two or more thereof. Also suitable are the reaction products of polyhydric alcohols such as glycerol, trimethylol ethane or trimethylol propane, pentaerythritol or sugar alcohols or mixtures of two or more thereof with the alkylene oxides mentioned to form polyether polyols. These polyether polyols are available as compositions, homopolymers or statistical or block copolymers of various molecular weights. Another group of polyether polyols are polytetramethylene glycols, which can be prepared by polymerization of tetrahydrofuran.

Polyetherglycols having a low molecular weight of less than 500 g/mol are also suitable.

Other examples of low molecular weight polyols are low molecular weight diols and triols, for example C ₂ to C ₂₀ diols such as ethylene glycol, propylene glycol, 1,2-butanediol-1,2 or 1,4-butanediol, 1,5 -pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,12-dodecanediol, dimeric fatty alcohols or higher homolog diols or isomers thereof. Additionally, polyols having more than three functional groups may be used, such as glycerol, trimethylol ethane, pentaerythrite and/or trimethylol propane, or higher functional alcohols such as sugar alcohols.

The composition may further comprise a polyol that is a hydroxy-functionalized polymer, for example a hydroxy-functionalized siloxane. Exemplary siloxanes that may be used are hydroxy-functionalized polydimethylsiloxanes, particularly those in liquid form, such as under the name Tegomer® H-Si 2311 (Evonik) having a molecular weight Mn of about 2,200 g/mol. , Germany) are commercially available. Suitable polydimethylsiloxane (PDMS) polyols are described, for example, in US 6794445 B2. It can be used in an amount of up to 60 wt %, based on the total weight of the polyol used, and typically has a low T _g value, for example in the range of -150 to -100 °C.

The hydroxyfunctional polybutadiene, known under the commercial name of Poly-bd®, is also suitable for use in the present invention.

In preparing the resin component (a), one or more of the polyols described above may be reacted with at least one polyisocyanate to form a hydroxyl-terminated polyurethane prepolymer. The one or more polyols are used in a molar excess relative to the NCO groups of all polyisocyanates present in the reaction mixture, so that after all the NCO groups have fully reacted, an OH-terminated polyurethane prepolymer is obtained. In certain embodiments, the NCO:OH ratio of the NCO-reactive polyurethane prepolymer is from 1:1.5 to 1:5.

Suitable polyisocyanates for use in the preparation of hydroxyl-terminated polyurethane prepolymers are known in the art and may include monomeric isocyanates containing two or three NCO groups. For example, it includes the well-known aliphatic, cycloaliphatic or aromatic monomeric diisocyanates. Preferably, the isocyanate has a molecular weight of 160 g/mol to 500 g/mol, for example an isomer of an aromatic polyisocyanate, for example diphenylmethanediisocyanate (MDI), such as 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,2'-diphenylmethane diisocyanate (2,2'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI); isomers of phenylenediisocyanate, such as 1,3-phenylenediisocyanate, 1,4-phenylenediisocyanate; isomers of naphthalene-1,5-diisocyanate (NDI), toluenediisocyanate (TDI) such as 2,4-TDI and 2,6-TDI; m- and p-tetramethyl xylylene diisocyanate (TMXDI), m- and p-xylylene diisocyanate (XDI), 3,3'-dimethyldiphenyl-4,4'-diisocyanate (TODI), toluene diisocyanates, naphthalenes, di- and tetraalkyl diphenylmethane diisocyanates, 4,4'-dibenzyl diisocyanates, and combinations thereof.

aliphatic and cycloaliphatic isocyanates such as ethylene diisocyanate, dodecane diisocyanate, dimer fatty acid diisocyanate, 4,4'-dibenzyldiisocyanate, 1,6-diisocyanato-2,2,4-trimethylhexane, Butane-1,4-diisocyanate, hexane-1,6-diisocyanate (HDI), tetramethoxybutane-1,4-diisocyanate, 1,12-diisocyanato-dodecane, 4,4'- Dicyclohexylmethanediisocyanate, 1,3-cyclohexane or 1,4-cyclohexane diisocyanate, 1-methyl-2,4-diisocyanato-cyclohexane, 1-isocyanatomethyl-3-iso Cyanato-1,5,5-trimethylcyclohexane (isophorone diisocyanate, IPDI), hydrogenated or partially hydrogenated MDI ([H]12MDI (hydrogenated) or [H]6MDI (partially hydrogenated) and combinations thereof are also can be used

It is also possible to include at least partially oligomeric diisocyanates from diisocyanates, for example HDI, MDI, IPDI or other isocyanates, such as allophanates, carbodiimides, isocyanurates, biuret condensation products. Polymeric MDI may also be used. Mixtures of aliphatic or aromatic isocyanates may be used. More preferably, aromatic diisocyanate may be used.

In certain embodiments, the at least one NCO-reactive prepolymer of resin component (a) has a number average molecular weight in the range of 400 to 100,000, preferably 1,000 to 50,000 g/mol, more preferably 5,000-50,000 g/mol. has M _n .

In an alternative embodiment, the resin component may comprise the polyols described above as is, optionally in combination with the prepolymers described above.

Additionally, the adhesive composition according to the present invention comprises a curing agent component (b). According to a preferred embodiment of the invention, the curing agent component (b) comprises at least one polyisocyanate. The polyisocyanate may be selected from those disclosed above with respect to the prepolymer.

In one embodiment of the invention, aromatic diisocyanates are preferred as polyisocyanates, while in another embodiment, mixtures of aliphatic and/or cycloaliphatic isocyanates with aromatic isocyanates are preferably used.

The viscosity of the at least one polyisocyanate comprised in the curing agent component (b) is preferably less than 80 mPa·s, particularly preferably 30 to 60 mPa·s (DIN ISO 2555, Brookfield RVT, No. 3 spindle) , 25 °C; 50 rpm).

The polyurethane adhesive composition according to the invention further comprises at least one adhesion promoter. At least one adhesion promoter may be included in component (a), component (b) or both component (a) and component (b) of the adhesive composition according to the invention. According to the invention, the at least one adhesion promoter is N-ethyl-2-pyrrolidone and/or methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate. However, among the above-mentioned two adhesion promoters according to the invention, methyl-5-(dimethylamino)- 2-methyl-5-oxopentanoate is preferably used. Thus, according to a particular embodiment, the at least one adhesion promoter is methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate. Accordingly, in various embodiments, the compositions described herein may be essentially free of NEP, ie, free of any intentionally added NEP in large amounts.

N-ethyl-2-pyrrolidone is a compound of the formula:

Methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate is a compound of the formula:

Surprisingly, the incorporation of N-ethyl-2-pyrrolidone and/or methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate as adhesion promoters into polyurethane-based adhesive compositions can be applied to various surfaces. It has been found that the adhesion of each composition to the skin can be improved. In particular, the adhesion of the respective polyurethane-based adhesive composition can be improved on a surface made of a plastic material, such as polyvinylchloride (PVC).

Without wishing to be bound by theory, methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate causes plastic surfaces, particularly those based on PVC, to soften and swell, thereby causing adhesion of the adhesive composition applied thereto. is thought to promote

In various embodiments, the at least one adhesion promoter N-ethyl-2-pyrrolidone, methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate or mixtures of the foregoing comprises a polyurethane adhesive composition It is present in the adhesive composition according to the invention in an amount of 1-10 wt %, preferably 3-7 wt %, based on the total weight of

The adhesives according to the invention may also contain other auxiliary substances which are preferably fully or partially mixed with the resin component. Adjuvants generally refer to substances added in small amounts to modify the properties of an adhesive in a desired direction, such as viscosity, wetting behavior, stability, reaction rate, or shelf life. Such additives for the improvement of specific properties include, for example, antifoaming agents, wetting agents or surfactants such as stearate, silicone oils and addition products of ethylene oxide or propylene oxide with fatty alcohols; UV stabilizers antioxidants such as those of the sterically hindered phenol, thioether, substituted benzotriazole or HALS type; Additional adhesion promoters, for example silanes containing hydrolysable groups, such as hydroxy functional, (meth)acryloxy functional, amino functional or epoxy containing methoxy, ethoxy, propoxy or butoxy groups functional trialkoxysilane; and flame retardants.

To enhance the reactivity of the adhesive to crosslinking, the adhesive may optionally contain a catalyst. Suitable catalysts that can be used according to the invention are in particular organometallic and/or amine-based catalysts. Examples are titanates such as tetrabutyl titanate or tetrapropyl titanate, dibutyl tin dilaurate (DBTL), dibutyl tin diacetate, tin octoate, dibutyl tin oxide, chelating metals such as Zr-acetyl Acetonate, Ti-acetylacetonate, Fe-acetylacetonate, amino compounds such as triethylenetetramine, triethylenediamine diethylaminopropylamine, morpholine, N-methylmorpholine, 1,8-diazabicyclo- [5,4,0]-undecene-7 (DBU), cyclohexylamine, 2-ethyl-4-methylimidazole. The catalyst is preferably incorporated into the curing agent component.

Another group of additives are tackifying resins. Resins are known as synthetic or natural resins in various compositions and types. Examples for such resins are abietic acid, abietic acid esters, terpene resins, terpene/phenol resins, poly-α-methylstyrene or aliphatic, aromatic or aromatic/aliphatic hydrocarbon resins or coumarone/indene resins.

Optionally, the adhesive may contain pigments or fillers. These additives can be used to modify certain properties of the adhesive. Examples are oxides, silicates, sulfates, phosphates or carbonates of Ti, Zr, Al, Fe, Mg, Ca, Ba or Zn, such as natural, ground chalk, precipitated chalk, barite, talc, mica, carbon black, titanium dioxide, iron oxide , aluminum oxide, zinc oxide, zinc sulfate or silicon dioxide. Water-absorbing powders such as zeolites may also be present as fillers. The filler should be present in finely divided form, for example having a size of from 1 to 200 μm, in particular up to 50 μm, but it can also be a nano-scale pigment.

The composition may further contain silicon dioxide. Examples include treated silica, precipitated silica, and untreated silica, with pyrolytic silica or fumed silica being particularly useful.

The composition may further comprise an additional polymer containing a plurality of carboxylic acid groups and/or hydroxyl groups. Such components may be selected, for example, from polycarboxylic polyhydroxy acid amides, polycarboxylic acid amides, and modified polyhydroxy ureas. Such polymers are known as physical thixotropic agents and are commercially available. It is disclosed, for example, in US Pat. No. 6,420,466 or EP1048681.

In principle, various additives and auxiliaries may be included in the respective components. However, it is useful to select such additives that do not react with the other compounds of component (a) or (b). In certain embodiments, a catalyst is added to component (b).

Methods for preparing both the resin component (a) and the curing agent component (b) are known in the art. Store both ingredients individually until use. For use, the resin and hardener components are mixed with each other in a manner known per se. After mixing the resin component (a) and the curing agent component (b), the ratio of the isocyanate groups present in the adhesive composition to the OH groups present in the adhesive composition is generally in the equivalent range, but with respect to the moisture present on the surface. It is convenient to provide a slight excess of isocyanate groups. The NCO/OH ratio should be between 0.90:1 and 1.5:1, in particular between 1.0:1 and 1.3:1.

The polyurethane adhesive of the present invention is liquid at the application temperature. The polyurethane adhesive of the present invention is preferably liquid at room temperature. In various embodiments, the adhesive composition according to the invention comprises from 500 to 100,000, in particular from 1,000 to 20,000 at a temperature of 40°C, as determined according to DIN ISO 2555 (Brookfield Viscometer RVT, No. 4 spindle, 25°C;. 5 rpm). It has a viscosity of mPas. The adhesives described herein may contain one or more solvents or may be solvent-free. Suitable solvents known to the person skilled in the art are in particular esters, ketones, halogenated hydrocarbons, alkanes, alkenes and aromatic hydrocarbons. Specific examples of suitable solvents are methylene chloride, trichlorethylene, toluene, xylene, butyl acetate, amyl acetate, isobutyl acetate, methyl isobutyl ketone, methoxybutyl acetate, cyclohexane, cyclohexanone, dichlorobenzene, diethyl ketone. , di-isobutyl ketone, dioxane, ethyl acetate, ethylene glycol monobutyl ether, ethylene glycol monoethyl, 2-ethylhexyl acetate, glycol diacetate, heptane, hexane, isobutyl acetate, isooctane, isopropyl acetate, methyl ethyl ketones, tetrahydrofuran or tetrachlorethylene, or mixtures of two or more of the solvents mentioned. In a preferred embodiment, the polyurethane adhesive composition according to the invention is solvent-free.

The adhesive may be applied to the substrate by any known technique including, but not limited to, spraying, painting, dip-coating, spin-coating, printing, and the like.

Accordingly, another embodiment of the present invention is a method of using the polyurethane adhesive composition according to the present invention. In various embodiments, such methods comprise applying an adhesive composition to a surface of a substrate, wherein the adhesive is a polyurethane adhesive composition as described above. In the process according to the invention, the two components (a) and (b) of the adhesive are mixed immediately before application. The adhesive composition is subsequently applied to the surface of the substrate.

Another embodiment of the present invention is a bonded structure consisting of a substrate, a cured adhesive and a second substrate, wherein the cured adhesive is an adhesive as described above comprising components (a) and (b). obtainable from the composition, which is applied and forms an adhesive layer after application to a substrate. The adhesive layer so applied provides a bonding layer between the substrates that is stable as a structural bond under various conditions of use.

Another object of the present invention is methyl-5-(dimethylamino)-2-methyl-5-oxo, respectively, as adhesion promoter for adhesive compositions, preferably for polyurethane-based adhesive compositions, in particular for two-component polyurethane adhesive compositions. the use of pentanoate and the use of N-ethyl-2-pyrrolidone.

It is to be understood that all embodiments disclosed herein with respect to methods are similarly applicable to the disclosed dispersions, compositions, and uses and vice versa.

The following examples are given to illustrate the invention. Since these examples are given for purposes of illustration only, the present invention should not be limited thereto.

Example section

Example 1:

Results obtained with respect to tensile shear strength of polyurethane adhesive compositions containing methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate (MDMO) or NEP or containing no adhesion promoter

<Table 1>

The above results show that both NEP and MDMO increase the tensile shear strength on PVC and aluminum substrates compared to the composition without adhesion promoter.

Example 2:

The wetting behavior of various additives was studied. Both methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate and N-ethyl-2-pyrrolidone (NEP) cause the PVC surface to soften and swell. These observations are believed to suggest the ability of the additive to promote adhesion to plastics.

Another additive also exhibiting this behavior was a mixture of 55-65% dimethyl glutarate and 15-25% dimethyl succinate and 10-25% dimethyl adipate.

These were not pursued during product development, because the tensile shear strength values on PVC (about 5 MPa) were not as high as formulations using methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate. , compared to 7 MPa for formulations based on NEP or methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate).

Methylethylketone (MEK) was also found to exhibit this wetting behavior and also exhibited adhesion to PVC, similar to the composition containing NEP/MDMO. These additives were no longer sought because of their flammability ratings.

Claims (10)

a resin component (a) and a curing agent component (b), and as an adhesion promoter methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate, or methyl-5-(dimethylamino)-2- A two-component polyurethane adhesive composition further comprising methyl-5-oxopentanoate and N-ethyl-2-pyrrolidone. According to claim 1,
a) the resin component (a) comprises at least one NCO-reactive prepolymer and the curing agent component (b) comprises at least one polyisocyanate;
b) the resin component (a) comprises at least one NCO-terminated prepolymer and the curing agent component comprises at least one polyol.
A two-component polyurethane adhesive composition. 3. The method of claim 2, wherein the at least one NCO-reactive prepolymer of resin component (a) has a number average molecular weight M _n in the range from 400 to 100,000, or from 1,000 to 50,000 g/mol, or from 5,000 to 50,000 g/mol. A phosphorus two-component polyurethane adhesive composition. 4. The two-component polyurethane adhesive composition according to claim 2 or 3, wherein the NCO:OH ratio of the NCO-reactive polyurethane prepolymer is from 1:1.5 to 1:5. 4. The method of any one of claims 1 to 3, wherein methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate, or methyl-5-(dimethylamino)-2-methyl-5- A two-component polyurethane adhesive composition, wherein oxopentanoate and N-ethyl-2-pyrrolidone are included in an amount of 1-10 wt%, or 3-7 wt%, based on the total weight of the polyurethane adhesive composition. 4. The two-component polyurethane adhesive composition according to any one of claims 1 to 3, wherein the NCO/OH ratio is from 0.90:1 to 1.5:1, or from 1.0:1 to 1.3:1. 4. The two-component polyurethane adhesive composition according to any one of claims 1 to 3, wherein the composition further comprises a further additive. 4. The two-component polyurethane adhesive composition according to any one of claims 1 to 3, wherein the adhesive composition comprises methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate as an adhesion promoter. . An adhesive composition comprising methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate as an adhesion promoter. delete